C++ 接雨水，不看后悔系列,解一道高频面试题

Posted 2022-11-28 灯火阑处

这是一道同事讨论过的一道趣味题，综合了比较多的解题思想，其中有二分，递归，分治等思想。闲来抽空实现了下，如有错误请多多指出,或者有优化处请多多指出。逻辑不是很复杂，直接上代码吧。

//
//  main.cpp
//  面试题经典
//
//  Created by 于磊 on 2020/5/27.
//  Copyright © 2020 于磊. All rights reserved.
//

#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;
typedef vector<int>::const_iterator c_iter;
int Area = 0;

size_t Max(c_iter begin,c_iter end,const vector<int> water)
    return *max_element(begin, end);

size_t MaxIndex(c_iter begin,c_iter end,const vector<int> water)
    return max_element(begin,end) - begin;


int getAreaL(c_iter _begin,c_iter _end,const vector<int> _water )
    if (_begin == _end) 
        return 0;
    
    size_t _idx = MaxIndex(_begin, _end,_water);
    size_t _max = Max(_begin, _end,_water);
    if (_idx>0) 
        getAreaL(_begin, _begin +_idx, _water);
    
    while (_begin+_idx!=_end) 
        Area+=_max-*(_begin++ +_idx);
    
    return 0;


int getAreaR(c_iter _begin,c_iter _end,const vector<int> _water )
    if ( _begin-1 == _end ) 
        return 0;
    
    size_t _idx = MaxIndex(_begin, _end,_water);
    size_t _max = Max(_begin, _end,_water);
    auto maxIdx =_begin+_idx+1;
    if ( _idx<_end-_begin-1) 
        getAreaR(maxIdx, _end, _water);
    
    
    while (_begin!=maxIdx) 
        Area+=_max-*(_begin++);
    
    return 0;


int main(int argc, const char * argv[]) 
    vector<int> water;
    int i;
    std::cout << "please input number of water container end of by #\\n";
    while (cin >> i && i != '#') 
        water.push_back(i);
    
    size_t _idx = MaxIndex(water.begin(), water.end(),water);
    getAreaL(water.begin(), water.begin()+_idx, water);
    getAreaR(water.begin()+_idx, water.end(), water);
    cout<<"总共装水 "<<Area<<endl;
    return 0;